1. Field of the Invention
The present invention relates to a processing device and method for a piezoelectric actuator used, for example, to inspect piezoelectric bodies of a disk drive suspension provided with piezoelectric actuators.
2. Description of the Related Art
A hard disk drive (HDD) is used in an information processing device, such as a personal computer. The disk drive comprises a magnetic disk that rotates around a spindle, actuator arm, positioning motor, etc. The actuator arm is configured to be turned transversely relative to the tracks of the disk around a pivot by the positioning motor. A suspension is mounted on the actuator arm. A slider that constitutes a magnetic head is disposed on the distal end portion of the suspension.
A DSA suspension (suspension with dual-stage actuator) is proposed to cope with the increase in the recording density of a hard disk drive. An example of the DSA suspension is disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2002-184140 (Patent Document 1). This suspension comprises an actuator arm, which is turned by a positioning motor, and a piezoelectric actuator (microactuator), which comprises a piezoelectric body. The piezoelectric actuator is adapted to move the suspension transversely relative to the tracks of a disk at high speed for an infinitesimal distance.
A piezoelectric body of, for example, lead zirconate titanate (PZT) is used for the piezoelectric actuator. This piezoelectric body is disposed between first and second electrodes. The first electrode is connected to a first conductive portion by a conductive resin, such as silver paste. The second electrode is connected to a second conductive portion. The conductive resin comprises a matrix resin and metallic fillers of silver particles or the like mixed in the matrix resin.
If the piezoelectric body in the disk drive suspension with the piezoelectric actuator is cracked, its properties are degraded. If the properties of the piezoelectric body are degraded, the suspension cannot display its predetermined performance. Thus, in a suspension inspection step, the properties of the piezoelectric body are checked for normality. For example, Jpn. Pat. Appln. KOKAI Publication No. 2003-141832 (Patent Document 2) discloses a disk drive that can determine whether or not a piezoelectric body is normal. In this disk drive, an AC voltage is applied to the piezoelectric body, and the capacitance (or electrostatic capacity) of the piezoelectric body is detected.
Depending on the mixing condition of the metallic fillers in the matrix resin of the conductive resin in the piezoelectric body, the value of electrical resistance may vary due to insufficient conduction between the fillers. The variation of the electrical resistance value not a little influences the result of the inspection. In some cases, therefore, a step of causing dielectric breakdown in the metallic fillers may be performed before the capacitance of the piezoelectric body is measured. If a relatively high voltage (e.g., 12V DC) is applied to the conductive resin, for example, dielectric breakdown occurs between the metallic fillers. By this dielectric breakdown, the continuity of the conductive resin can be secured, and the value of electrical resistance can be stabilized.
Conventionally, as mentioned before, the step of causing dielectric breakdown by applying the relatively high DC voltage to the conductive resin and the step of measuring the capacity of the piezoelectric body by the AC voltage are performed separately. Thus, the operation for inspecting the piezoelectric body takes a lot of time and labor.